If you’ve heard of the Gilt Groupe, you’re either a fashion junkie, or you’re one of those folks who marvels at insanely demanding logistics infrastructures.

Gilt Groupe is a private-sales site, one of those trendy e-commerce retailers that requires membership, takes the intimacy of customer knowledge and service to unprecedented levels, and creates incredible profit on a surprisingly high volume of sales. The benefit to the Gilt Groupe customer comes not just in the form of great service, but discounts of up to 60% on otherwise pricey fast-fashion, home décor, travel destinations, and artisanal ingredients for culinary enthusiasts. It’s a somewhat eclectic mix of merchandise, and the fun part for the retailer’s customers is that many of its sales happen in pop-up or “flash” style, with brief windows of opportunity to get a great deal on a hot fashion, travel deal, or culinary gift. It’s an e-commerce iteration of the New York style, invitation-only high-brow sample sale — at a discount. When the stock is gone, the sale is done.